Objective: To evaluate the relationship between surgical outcomes with the subacute pre-emptive thoracic endovascular aortic repair (PTEVAR) and the factors related to a change in aneurysm diameters for uncomplicated acute type B aortic dissection (UATBAD). Methods: From December 2008 to January 2020, total 38 patients (shrinkage(S) group; 32, non-shrinkage(N) group; 6) were followed up one year after pre-emptive TEVAR for UATBAD. Their relationship with preoperative, postoperative factors and computed tomography findings (Parsa classification) was analyzed retrospectively. Results: Factors for the statistically significant changes in aneurysm diameters were, with or without preoperative reentry, loss of false lumen within 6 months after surgery, and attribution to Parsa classification 3 in the S group, and preoperative iliac region reentry, full false lumen patency, central landings in zone 2, postoperative type Ia EL, type V EL, and Parsa classification 0 for in the N group.For additional treatments, two patients in the N group underwent open repair, chimney TEVAR and one patient in each group required re-entry closure with re-intervention. Conclusions: Subacute PTEVAR was effective for uncomplicated acute type B aortic dissection (UATBAD), but the cases showing extensive dissection, zone 2 landing, and a postoperative extensive residual false lumen had a tendency not to reduce the aneurysm diameter.